The Solana solar farm located 70 miles southwest of Phoenix, Arizona is the first in the United States to use molten storage technology. It still uses hundreds of parabolic-shaped mirrors to focus the sun’s rays, but unlike other concentrated solar power (CSP) facilities, it also uses tanks of molten salt to store huge amounts of heat for long periods of time. This feature allows energy production to continue even when the sun has gone down, making it a breakthrough for the country’s renewable energy industry. At a cost of $2 billion, the CSP facility was developed by Spanish company Abengoa Solar and took nearly three years to build.
Solar power gets poor press because it can’t provide continuous power the way non-sustainable sources such as coal and natural gas can. The solar farm in Arizona deals with this problem by collecting heat from the sun while at its peak, and then channeling the collected energy into molten salt tanks. When the sun goes behind a cloud, or as night begins to fall, the solar farm can continue to generate power using these reserves for another six hours.
There are two core technologies that power these types of solar farms: “parabolic trough” technology, or “power tower” technology, which uses mirrors and lenses to focus light onto central towers. Solana uses the former, but is also the first CSP facility to start using molten salt thermal storage technology in the U.S., while most others still rely on concentrating sun light to produce heat and drive turbines directly. Just to make the distinction clear, solar farms are also different from solar panels, which directly convert the sun’s light into electricity.
Apart from its thermal storage technology, the facility is unique because of the controversy it caused in 2010 when it received a $1.5 billion loan guarantee from the Department of Energy. Despite the controversy, it would appear the DoE’s commitment to back up the loan was money well spent since the 280MW facility is expected to provide electricity for 70,000 households – all of which Arizona’s largest utility Arizona Public Service (APS) will purchase.
Images via Abengoa Solar